Carboxylation of cyclopentadiene

ABSTRACT

Method of carboxylating an organic compound of the group of RC*CH, RCH2CN, indene or cyclopentadiene where R is hydrocarbyl comprising contacting under anhydrous conditions in an inert atmosphere and in the presence of an inert, aprotic, dipolar, liquid solvent, said compound with a carbonated metal phenoxide, the metal phenoxide of the formula: WHERE X is sodium or potassium, R1 is hydrogen or alkyl, and subsequently acidifying the resultant intermediate product to form the carboxylated product.

United States Patent [191 Patmore et al.

[111 3,725,468 51 Apr. 3, 1973 [54] CARBOXYLATION 0F CYCLOPENTADIENE[75] Inventors: Edwin L. Patmore, Fishkill; William R. Siegart; HarryChafetz, both of Poughkeepsie, all of N.Y.

[73] Assignee: Texaco Inc., New York, N.Y.

22 Filed: Nov. 10, 1971 [21] Appl. No.: 197,529

Related 0.8. Application Data [62] Division of Ser. No. 794,344, Jan.27, 1969, Pat. No.

2,342,385 2/1944 Wallingford ..260/405 X OTHER PUBLICATIONS Krauch etal., Organic Name Reactions, PP. 273-274, (1964) PrimaryExaminerLorraine A. Weinberger Assistant Examiner-Robert.GerstlAttorney-K. E. Kavanagh et al.

[57] ABSTRACT Method of carboxylating an organic compound of the groupof RC 5 CH, RCI-I,CN, indene or cyclopentadiene where R is hydrocarbylcomprising contacting under anhydrous conditions in an inert atmosphereand in the presence of an inert, aprotic, dipolar, liquid solvent, saidcompound with a carbonated metal phenoxide, the metal phenoxide of theformula:

where X is sodium or potassium, R is hydrogen or alkyl, and subsequentlyacidifying the resultant intermediate product to form the carboxylatedproduct.

5 Claims, No Drawings CAR BOXYLATION OF CYCLOPENTADIENE This is adivision, of application Ser. No. 794,344 filed Jan. 27, 1969 now US.Pat. No. 3,658,874.

BACKGROUND OF INVENTION The subject invention is found in the field ofart relating to the introduction of a carboxylic acid group into organiccompounds. In the past, in order to carboxylate the starting compoundscontemplated herein utilizing carbon dioxide the contacting had to beaccomplished in the presence of relatively expensive bases such assodium, naphthalene, n-butyl lithium and sodium hydride. Due to the costof the base, the prior art methods of carboxylating the reactantscontemplated herein had only limited commercial prospects.

SUMMARY OF INVENTION where X is sodium or potassium and R is hydrogen oralkyl of from one to 12 carbons and subsequently acidifying theresultant reaction mixture to recover the carboxylic acid product.

The discovery that the carbonated metal phenoxide salts facilitate theproduction of carboxylated products 4 in high yields has rendered a basecatalyzed carboxylation process for the starting materials contemplatedherein commercially feasible since the carbonated resultant mixture torespectively'form carboxyl comphenoxide is many times less expensivethan previous bases employed. Further, the subject -method has severaladvantages over the method set forth in our coassigned, copendingapplication Ser. No. 784,901 filed Dec. 18, 1968, now US. Pat. No.3,595,907, wherein carboxylation occurs by contacting the organic reac-.tant with carbon dioxide in the presence of uncarbonated metal phenoxidefollowed by acidification. These several advantages are a substantialreduction in the amount of carbon dioxide required, a better control ofthe reaction and with some reactants superior yields.

DETAILED DESCRIPTION OF THE INVENTION pounds of the group of R-C 5 COOH,

COOH Rt'JHGN indene-3-carboxylic acid and tricyclo [5.21.0

deca-3,8-diene-4,9dicarboxylic acid. The carbonated metal phenoxide isprepared by contacting with an excess of carbon dioxide a metalphenoxide of the formula:

where X and R are as heretofore defined at a temperature between about 0and 150 C. under a carbon dioxide pressure of between about 1 and 200atmospheres and in the presence of inert aprotic, dipolar, liquidsolvent. The reaction of the organic reactant and carbonated phenoxideunder preferred conditions takes place at a temperature between 25 and50 C., at a carbon dioxide pressure of between 1 and 25 atmospheresutilizing a mole ratio of said carbonated phenoxide to said organiccompound of between about 4:1 and 10:1. By the term excess of carbondioxide to metal phenoxide it is hereinbefore and hereinafter intendedto denote a mole ratio of at least about 2:1 and up to 100:1 and more.

The preparation of the carbonated metal phenoxide reactant. underpreferredconditions takes place at a temperature between 25 and 50 C'.,a carbon dioxide pressure between 1 and 25 atmospheres, a mole ratio ofcarbon dioxide to phenoxide of between about 2:1 and 10:1 and in thepresence of an inert, aprotic, dipolar, liquid solvent.

Acidification desirably takes place at a temperature between about 5 and35 C. to a pH between about 1 and 3 to convert the intermediate productto the desired carboxylic acid derivative. A pH up to about 6 is alsosuitable.

The carboxylic acid products are recovered from the (I) represented bythe formula:

, I the" complex of the phenoxidesalt with carbon dioxide (ll)represented by the formula:

and an unidentified material III where X and R are as heretoforedefined. Compounds I and III are in nearly equal amounts and werepresent in slightly larger amounts than Compound II.

Examples of the organic reactant compounds contemplated herein arephenylacetylene, benzyl cyanide, acetonitrile, hexanenitrile, acetylene,l-butyne and lhexyne.

Examples of the carbonated reactants are the carbonated sodium andpotassium salts of phenol, methylphenol, t-octylphenol, nonylphenol anddodecylphenol.

Specific examples of the acidifying acids contemplated herein are themineral acids such as hydrochloric acid, nitric acid, sulfuric acid andhydrobromic acid in aqueous concentrations ranging from 4 to 96 wt.percent.

Specific examples of the liquid solvents contemplated herein for thepreparation of the carbonated phenoxide salt and the carbonatedsalt-organic reactant intermediate product are N,N-dimethylformamide,hexamethylphosphoramide, dimethyl sulfoxide, diphenyl sulfoxide,dimethyl sulfone and N,N-dimethyl acetamide. The quantity of solventemployed advantageously constitutes between about 50 and 90 weightpercent of the reaction mixture. Further, any inert, aprotic, dipolar,liquid (under conditions of reaction) solvent is suitable.

Examples of gases which can form the inert atmosphere are nitrogen,helium and argon.

Specific examples of the carboxylic acid products contemplated hereinare indene-3carboxylic acid, tricycle-[5 .2- 1 .0 deca-3,8-diene-4,9-dicarboxylic acid, phenylpropiolic acid,alpha-phenylcyanoacetic acid, alpha-cyanohexoic acid, Z-butynoic acid,2- propynoic acid and 2-hexynoic acid.

One of the important aspects of the method of the invention is themaintenance of anhydrous conditions during the preparation of thecarbonated phenoxide salt and the carbonated salt-organic reactantintermediate. If such conditions are not observed, little or no yield ofsalt reactant and intermediate are obtained resulting in no yield ofdesired carboxylic product. Another important aspect of the method ofthe invention is the employment of a carbonated phenoxide salt toorganic reactant of at least about 2:1. Lesser ratios result in littleor no carboxylic product.

The following examples further illustrate the invention but are not tobe considered as limitations thereof.

EXAMPLE I This example illustrates the preparation ofalphaphenylcyanoacetic acid from benzyl cyanide.

Sodium phenoxide (25.6 grams, 0.24 mole) and dimethylformamide 100 mls.)were charged to a three-necked, 250 mls. flask equipped with a magneticstirring bar, thermometer, gas sparger and water cooled condenser fittedwith an expansion bulb. The exit of the expansion bulb was connected toa mercury bubbler to protect the system from the atmosphere. Dry carbondioxide was bubbled into the clear brown solution. The temperature rosefrom 33 to 46 C. and the contents of the flask became a milky,grey-brown mixture. After 20 minutes the temperature dropped to 34 C.Foaming was observed at this point. Excess carbon dioxide was bubbledinto the solution and after approximately an hour the mixture started toclear and the solids dissolved. Carbon dioxide was passed into thereaction mixture for a total of 3 hours. Carbon dioxide blowing wasdiscontinued and replaced by a stream of dry nitrogen (sequentiallypassed through concentrated sulfuric acid and then soda lime). Benzylcyanide (7 grams, 0.06 mole) was charged to the flask with an additionall5 mls. of dimethylformamide. The mixture was stirred for 3 hours undernitrogen. The nitrogen was removed and the system closed and the mixtureallowed to stand overnight.

The reaction mixture was poured into a beaker containing 100 grams ofice and 100 mls. of concentrated l-ICI. The aqueous acidic layer wasextracted with ether (6Xl00 mls.). The combined ether layers wereextracted with 10 percent sodium bicarbonate (5 l00 mls.). Thebicarbonate extracts were cooled in an ice bath and made acidic with 6molar hydrochloric acid. The acidified solution was extracted with ether(6X100mls.). The combined ether extracts were washed with water mls.)and dried over anhydrous sodium sulfonate and over anhydrous calciumsulfate. The solution was filtered and the ether removed on the rotaryevaporator to give 7.5 grams of acidic material which solidified uponstanding. An infrared spectral analysis confirmed the product asalpha-phenylcyanoacetic acid.

The crude alpha-phenylcyanoacetic acid was recrystallized from 55 mls.of benzene and 150 mls. of petroleum ether and the yield of purifiedacetic acid product was determined to be 64 mole percent. Elementalanalysis of the recrystallized product gave the following: Found: wt.percent C 66.9; wt. percent H 4.4; wt. percent N 8.4; Calc: wt. percentC 67; wt. percent H =43; wt. percent N 8.69.

The reactions of the above were conducted under atmospheric pressure.

EXAMPLE II This example illustrates the criticality. of employing atleast about a 2:1 mole ratioof carbonated phenoxide to organic reactant.

The procedure of Example I was essentially repeated with the exceptionthat 3.5 grams (0.03 mole) sodium phenoxide 75 mls. dimethylforrnamideand carbon dioxide were first reacted to form the intermediate andsubsequently 3.5 grams (0.03 mole) benzyl cyanide were added and themixture was stirred, acidified and worked up in the usual manner. Nocarboxylic acid material was isolated.

EXAMPLE III This example illustrates the criticality of maintaining ananhydrous reaction basically utilizing the general method and apparatusset forth in Example I with the following exceptions: Carbon dioxide wasbubbled into a solution of sodium phenoxide (28.3 grams, 0.24 mole) anddimethylformamide mls.) for 10 minutes. Then several drops of waterabout (0.09 grams) were added and an immediate cloudiness followed by asolid formation was observed. Carbon dioxide flow was maintained for atotal of 3 hours. Carbon dioxide was discontinued, benzyl cyanide (7grams, 0.06 mole) was added and the system closed to the atmosphere. Themixture was allowed to stir for approximately 3 hours and then allowedto stand overnight. The reaction mixture was then acidified and workedup. No carboxylic acid product was recovered.

EXAMPLE IV This example illustrates the desirability of having anextended reaction time between the sodium phenoxide and carbon dioxideto form the carbonated intermediate.

The procedure employed was essentially that of Example l. The reactivecarboxylated phenoxide was prepared by bubbling an excess of carbondioxide into a solution of sodium phenoxide (13.9 grams, 0.12 mole) anddimethylformamide (75 mls.) for approximately 24 minutes rather than the3 hour period in Example I (3246 C.). The carbon dioxide stream was thendiscontinued and the sparger replaced by a plug. Then benzyl cyanide(3.5 grams, 0.03 mole) was added and the mixture was stirred for 3hours. The mixture was allowed to stand overnight, acidified and workedup to give a crude acidic product which was recrystallized from benzene(35 mls.)-petroleum ether (75 mls.) to give 2.43 gramsalpha-phenylcyanoacetic acid in a yield of 50 percent which is somewhatless than the 64 percent yield of Example I.

EXAMPLE V This example illustrates the preparation of phenylpropiolicacid from phenylacetylene.

Utilizing the general procedure and apparatus described in Example 1with the following changes:

Carbon dioxide was bubbled into a solution of sodium phenoxide (13.0grams, 0.12 mole) and dimethylformamide (75 mls.) for 3 hours at 28-35C. Then phenylacetylene (6.2 grams, 0.06 mole) under nitrogen was addedand the mixture stirred 3 hours under nitrogen. The nitrogen stream wasdiscontinued, the system closed to the atmosphere, and the reactionmixture allowed to stand overnight. The product mixture was acidifiedand worked-up to give 2 grams of crude phenylpropiolic acid representinga mole percent yield of 23. A recrystallized sample of phenylpropiolicacid (from distilled water) gave white crystals, m.p. l36-13 7 andelemental analysis gave the following: Found: wt. percent C 74.0, wt.percent H 4.4; Calc.: Wt. percent C 73.97, wt. percent H 4.1.

EXAMPLE Vl This example further illustrates the preparation ofphenylpropiolic acid from phenylacetylene and when the yield is comparedto Example V this demonstrates the preferability of a 4:1 ratio ofcarbonated phenoxide to phenylacetylene reactant as opposed to the 2:1ratio used in Example V.

The procedure of Example V was essentially repeated with the exceptionthat the carbonated intermediate was forrned by the reacting 27.8 grams(0.24 mole) of sodium phenoxide with excess carbon dioxide in 100 mls.dimethylfonnamide. In the subsequent reaction of the carbonatedintermediate 6.2 grams (0.06 mole) of phenylacetylene was employed.Phenylpropiolic acid in an amount of 4.5 grams was recoveredrepresenting a yield of 51 percent or more than double that of ExampleV.

EXAMPLE v11 This example illustrates the preparation of indene-3-carboxylic acid from indene.

The procedure and apparatus employed was that in general described inExample I. The carboxylated sodium phenoxide intermediate was preparedby bubbling excess carbon dioxide into a solution of sodiumphenoxide(13.9 grams, 0.12 mole) and dimethylformamide mls.) for 3 hours. Thetemperature ranged from 20 to 38 C. The carbon dioxide was replaced bydry nitrogen. Then indene (3.5 grams, 0.03 mole) was added and themixture stirred for approximately 3 hours under nitrogen. The nitrogenflow was discontinued, the system closed to the atmosphere, and thereaction mixture allowed to stand overnight. The mixture was acidifiedand was worked up to give 4.7 grams of crude acidic material.

The crude acidic material was recrystallized from benzene to give 1.65grams of a product whose infrared and nuclear magnetic resonance spectrawere comparable to those of indene-3-carboxylic acid. This represented ayield of 34 mole percent. Elemental analysis of the recoveredindene-3-carboxylic acid Found: wt. percent C 75; wt. percent I-I 5;Calc.: wt. percent C 75; wt. percent H 5.

EXAMPLE VIII This example illustrates the preparation of Thieles acid,that is, tricyclo [5.21.0 deca-3,8-diene-4,9- dicarboxylic acid.

The procedure and apparatus broadly was that employed in Example 1.Carbon dioxide was bubbled into a solution of sodium phenoxide 13.9grams, 0.12 mole) and dimethylforrnamide (75 mls.) for 3 hours toprepare the reactive carboxylated phenoxide. The temperature ranged from21-42 C. The carbon dioxide stream was discontinued, the system wasclosed to the atmosphere and cyclopentadiene (4 grams, 0.06 mole) wasadded. The mixture was stirred for 3 hours and washed to give 2.5 gramsof Thieles acid having a melting point of 191193 C. The product wasconfirmed by infrared analysis. The yield basis cyclopentadiene was 38mole percent.

We claim:

1. A method of producing tricyclo[5.2-l .0 deca-3,8-diene-4,9-dicarboxylic acid comprising contacting a carbonated metalphenoxide with cyclopentadiene under anhydrous conditions and an inertatmosphere in a mole ratio of said carbonated phenoxide to saidcyclopentadiene of between about 2:1 and 20:1 at a temperature betweenabout 0 and C. under a pressure of between about 1 and 200 atmospheres,subsequently acidifying the resultant reaction product to a pH of lessthan about 6 and recovering said tricyclo[5.2-]deca-3,8-diene-4,9-dicarboxylic acid from the acidified mixture, saidcarbonated phenoxide being prepared by contacting under anhydrousconditions a base of the formula:

wt. percent of the reaction mixture.

3. A method in accordance with claim 2 wherein said acidifying isconducted to a pH of between about 1 and 3.

4. A method in accordance with claim 3 wherein said solvent is dimethylformamide and acidifying is conducted with hydrochloric acid. 7

5. A method in accordance with claim 3 wherein sai base is sodiumphenoxide.

2. A method in accordance with claim 1 wherein said solvent is presentin an amount between about 50 and 90 wt. percent of the reactionmixture.
 3. A method in accordance with claim 2 wherein said acidifyingis conducted to a pH of between about 1 and
 3. 4. A method in accordancewith claim 3 wherein said solvent is dimethyl formamide and acidifyingis conducted with hydrochloric acid.
 5. A method in accordance withclaim 3 wherein said base is sodium phenoxide.